جستجوی مقالات مرتبط با کلیدواژه « عوامل فیزیوگرافی » در نشریات گروه « اکولوژی »

This research aims to analyze vegetation changes in desert landforms in the northern region of Isfahan province using Landsat images 5 and 8, specifically TM5 and OLI-TIRS sensors, from 1987 to 2020. For this purpose, 200 images were extracted during the 27 warm months, from June 1 to the end of August. After performing the necessary pre-processing on the images that cover the study region, the landforms were classified using the Topographic Position Index (TPI). Subsequently, the NDVI index was analyzed. The results showed that the pattern of vegetation changes from mountainous areas to lowlands is downward. The analysis of the vegetation index on different landforms, as extracted from the TPI, revealed that the unit of mountains and heights exhibited the highest values, while flat plains such as playas, mud, and clay pans had the lowest values. In general, NDVI values have a decreasing trend from mountain landforms to playas, mud, and clay pans. A significant decrease in NDVI is evident at an altitude of 1400 m (middle pediments). NDVI values increase in mountainous landforms (elevations above 1400 m). On slopes greater than 65° (high stony and rocky lands), the decreasing trend of NDVI has intensified. The NDVI index illustrates four phases of change. The fourth phase, which spanned from 2014 to 2020, exhibited a decreasing trend. During this period, the area covered by this index decreased from 34,380 km² to 34,200 km². The spatial changes of the NDVI index in 2030 indicate that the elevations from Karkas to Marshenan and the areas between Kashan and Ardestan will experience critical conditions. This issue requires the special attention of relevant officials and executives in this field.

In many parts of the world, there is not enough precise information about suitable land for cultivation. Understanding climate and the required parameters during the growth period of crops is the mostimportant factor in the zoning Agroclimate. In Iran, lentils with acreage of 240 thousand hectares and the production of 166 thousand tons per year after the peas in second place is important. Agro-ecological zoning is one of the land evaluating method that can be used to find better lands and improve the planning and management of land resources. The purpose of this research, zoning Agroclimatic Ardabil Province for the cultivation of lentils, In order to identify the characteristics of land resources for the planning and organize and optimal land, Assessing of land suitability, in any of the zone by using AHP is Agroclimatic. Ardabil Province is in northwestern Iran, with an area of 17953 square kilometers, 1.09 percent of the country's total area. The present study was conducted across Ardabil Province which is located in 37° 25' and 39° 42' N latitude and between 47° 03' and 48° 55' E longitude. Data used in this research; climatic factors such as rainfall, temperature, relative humidity, sunshine duration and degree-days during the growing season are the data of 37 synoptic and meteorological and data physiographic such as elevation, slope, aspect, soil and land use map of the study area were collected from relevant organizations. By performing the necessary calculations using SPSS and EXCEL software, the database was frormed in GIS environment. Then for each of the parameters in the GIS environment with generalized point data, linear and polygon surrounding surfaces (Interpolation) were performed, as the data layers and maps. Each of the layers of the study, based on favorable climatic requirements lentils were categorized based on AHP. According to the purpose of this study, the role of the main criteria such as Climate, Soil, Physiography and land use criteria selected under Options AHP were calculated and then using the weighted important factor, weight and final weight of all criteria were determined.
Lentil planting zoning based on climatic factors: Data of climatic elements during the growing season lentils have an influential role. The sudden change of climate data is effective on crop yield. In this study, the rate of climate data based on hierarchical, weight coefficient was determined as follows: Temperature 0.382, precipitation 0.250, humidity 0.160, sunshine hours 0.101, evaporation 0.064 and wind 0.043. By overlaying maps of climatic elements, about 20.42 percent with a very suitable, 37.75 percent was suitable, 24.47 percent average and 17.34 percent of conditions are unsuitable for cultivation of lentils.
Zoning planting lentils, based on physiographic factors: For evaluation the cultivation of lentils, map each datas, elevation, slope and aspect were prepared in GIS environment. Based on the favorable climatic lentils product to physiographic factors, weighting layers were based on AHP. Therefore, the height by a factor of 0.614, slope 0.268 and slope were determined 0.117. By combining maps of physiographic province, 22.68 percent has a very suitable, 21.11 percent sutitable, 17.33 percent average and 38.86 percent conditions are unsuitable for cultivation of lentils.
Zoning lentil cultivation, on the basis of physiographic and climatic elements: By combining all the maps of climatic and physiographic factors that were prepared based on hierarchical method weighting coefficient, the final zoning map Agroclimate lentil cultivation in this province was prepared. Based on the final map, in Ardebil province about 17% very suitable, 32% was suitable, 27% moderately and 24% had poor conditions for the cultivation of lentils. This study aimed to Agroclimateland zoning for planning agriculture in the province of Ardabil. Based on the favorable climate condition for lentil crop, land evaluation of each data was done for production of lentils. So the the main criteria including; climate 0.565 factor, physiographic by a factor of 0.262, soil 0.188 and land the highest weight by a factor of 0.055 respectively has an effective role in the lentils, as well as minimum temperature during the growing season and maximum temperatures and low rainfall (during seed germination and flowering) altitude and the high slope is the limiting factor for the cultivation of lentils in the province.

  Pea plants are grown in hot and arid and semi arid weather conditions in cold areas in spring and autumn in the tropics. Iran is the fourth largest producer of peas in the world after India, Turkey and Pakistan. Despite the high-yielding cultivars development, weather is one of the most important determinants of the plant's performance. In this study, with the use of meteorological data, physiographic regions favorable for the cultivation of pea in Ardabil are identified. Collecting of data in this study is as follows. 1- Collecting climatic elements such as temperature and precipitation in the Province Ardabil during the period 1988 to 2013. 2- The preparation of topographic map with a scale of 1: 50,000 of the Armed Forces Geographical Organization. 3- Preparation maps of slope, elevation 4- Preparing soil maps and land use 5- Preparation of physiographic and climatic zonation map of pea cultivation of combining all data using AHP. In this study, each of the data after a review of the valuation methods were studied in GIS environment and the combination of the following options, criteria and sub-criteria, the final map was prepared. Precipitation play an important role in maintaining moisture and water requirement of pea. In this study, the amount of precipitation was used in the weather stations in April, May, June and July. Temperature is one of the decisive factors in the geography of plants and garden areas. Climatic factors such as: the distribution of the amount of rainfall during the growing of peas, average minimum temperature, germination, flowering temperature, temperature and relative humidity during their growth and climate elements by analyzing the data was about 37 percent very suitable, 21 percent suitable, 20 percent average and 22 percent was unsuitable for the cultivation of peas. Physiographic data played a significant role and is a limiting factor during the growing season of pea. The results of physiographic maps show that about 55 percent very suitable, 25 percent fair and 20 percent is unsuitable for cultivation of pea.
The aim of this study was to investigate the role of physiographic and climatic elements in the cultivation of pea, each of them prepared in different forms and was weighted, and results of zoning pea cultivation in this Province are as follows.
1. The areas are very suitable for cultivation of peas, plain and south of the cities of Ardabil is Meshkinshahr that is consistent with agricultural areas and there are no limitations for pea and constitute about 18 percent of Ardabil Province.
2. The regions in terms of Pea has the perfect conditions surrounding cities of Khalkhal and Sareyn, Kowsar and central areas of the city, Nir, northeast and constitute Meshkinshahr cities. A major constraint in the areas of water requirements and minimum temperature that is about 45 percent of the total area of the province.
3-Areas that slope, soil depth, elevation, temperature fluctuations are considered a major factor in limiting Pea-are the northern and southern areas and around the city Meshkinshahr form and about 27 percent of the total area of the province.
4-The areas of the Ardabil province due to the mountainous area, cold air and a lack of proper soil horizon with severe limitation is facing the possibility of planting about 12 percent of the Province Ardabil. In addition to the fact that peas are cultivated as human and animal food, the cultivation of this plant should be included in the crop pattern due to the contribution of soil fertility as one of the components of sustainable agricultural systems.
The final results show that:1- Among the main criteria, 0.603 climate, topography, 0.245, 0.114 soil and land use 0.038 higher priority on locating the pea are grown.
2-The results show consistency index criteria, all criteria are used with consistency index less than 0.1

Vegetation is the most important factor influencing the sustainability of rangeland ecosystems. Therefore, it is important to understand the environmental factors and their effect on vegetation and restoration of rangeland ecosystems. The aim of this study was to identify factors influencing on Gundelia tournefortii L. distribution. Accordingly, the information of Gundelia tournefortii L. was determined in six habitats in Isfahan province. Random- systematic sampling was conducted to calculate canopy and density of the species. In each rangeland place, climate, physiography and soil factors were identified. RDA ordination analysis using CANOCO software was used to investigate the vegetation relationship with environmental factors. In the cluster analysis and RDA ordination analysis, six main habitats of the species were classified into three groups. The first axis of ordination showed a very strong correlation with canopy cover and density and the second axis showed a very strong correlation with soil depth. According to study of the habitats of this species, annual precipitation about 250 to 500 mm, altitude 2300 to 2500 meter, slope about 10 to 40 percent and average of annual temperature about 10 ̊C to 12 ̊C are appropriate for presence of this species.

The aim of this study was to investigate the relationship between physical and chemical properties of soils with vegetation distribution in Divan-Darre rangeland as one of the most important rangelands in Kurdistan province. For this purpose، a random systematic 150 m × 200 m gird sampling plan was used to establish 90 sampling plots. In each plot، soil factors and percent cover of each plant species were recorded. The minimal area method was utilized to determine the sample size in the herbaceous layer in this study that it was obtained 4m2. Percent cover of each species was estimated base on the Braun-Blanquet criterion. Vegetation classification was done to determine ecological species group using Cluster method. Ward’s method used to calculate the distance amongst clusters، and Euclidean method for distance index was used. The result of clustering analysis was indicated that four ecological species groups were found. Multivariate analysis was performed to detect the relationship between the physiographic، soil factors and the ecological groups. The most important physiographic and soil factors in these communities were belonged to N، K، OC، OM، pH، SP%، soil texture (clay، sand، and silt)، EC، elevation، aspect and slope. Since each plant species has the specific ecological requirements to soil properties and physiographic factors، study of them can be used to improve vegetation restoration.